SKELETAL MUSCLE ARCHITECTURE CHANGES WITH AGING.

Abstract

1964 Skeletal muscle atrophy is a hallmark of aging, yet architectural changes in aging muscle are not well known. To study muscle architecture, two groups of elderly individuals (E1: 62.6±4.2 yrs, n=10, and E2: 73.5±1.8 yrs, n=12) and young controls (Y: 27.2±5.9 yrs, n=9) were used. Height, weight, and fat-free and fat-mass (7 skinfolds) were determined. Muscle architecture was measured with B-mode ultrasound: muscle thickness (MTH) of the quadriceps, hamstrings, tibialis anterior (TA), and gastrocnemius (CA) muscles; isolated MTH, and fascicle pennation angle (PANG) of vastus lateralis (VL) and gastrocnemius medialis (MG), and fascicle length (FASL) was estimated. Body weight, FFM, and %fat were not different among groups. Height was similar in E1 and E2 but less than Y. Upper-leg length was similar among groups, but Y had a greater lower-leg length. MTH was equivalent in E1 and E2, but significantly lower than Y at all sites. MG PANG (Y=20.6±1.8; E1=20.1±2.3; E2=18.7±4.2) was similar among groups, but in VL was less in E1 and E2 (E1=15.3±4.5; E2=14.0±2.9) than Y (19.6±3.8). VL FASL was similar among groups, but MG FASL was significantly less in E1 and E2 compared to Y, yet relative to segment length, VL and MG FASL were similar among groups. Muscle atrophy appears related to changes in MTH with decreased PANG with constant FASL (VL) or constant PANG with reduced FASL (MG). (Table)Table